Landslide Hazard: A Coupled Hydro-Mechanical Analysis with Variation of Suction and Soil Stiffness during Wetting Process – Ma River Case Study

Abstract

In this study a coupled hydro-mechanical analysis using FEM method was applied to simulate numerically the landslide process of the Ma river bank. The elasto-viscoplastic model was employed to investigate the unsaturated soil behaviour based on the Barcelona Basic Model (BBM-VP). The model allows taking into account the hardening and softening due to mechanical and hydraulic loading. For hydraulic behaviour, generalized Darcy's law is used with porosity dependant intrinsic permeability and employing a van Genuchten type relationship between suction and degree of saturation. For evaluation of the results obtained via the BBM-VP constitutive law, the landslide process was simulated employing two different material laws, and namely, the linear elastic viscoplastic Drücker-Prager type model accounting for suction and the linear elastic-perfect plastic Mohr-Coulomb model without considering the effect of soil suction. The evolution of displacements and the inelastic deformation during infiltration process are discussed based on the simulation of dry to rainy season water level change. We tried to assess the potential of a cou-pled hydro-mechanical model accounting for time dependent effects for quantifying stresses and deformations neces-sary to trigger slope failure.